Automatic alarm annunciator circuits



Dec.: 5,: 1967 R, R. WALSH 3,352008" AUTOMATIC ALARM ANNUNCIATOR CIRCUITS Filed March 17, 1964 2 Sheets-Sheet 1 INVENTOR:

Robert R. Walsh BY I FIGJ".

ATTORNEYS" 1967 R. R. WALSH 3,357,008

AUTOMATIC ALARM ANNUNCIATOR CIRCUITS Filed March 17, 1964 I 2 Sheets-Sheet 2 P4 yea P1 /P3 INVENTOR Robert RWdlsh ATTORNEYS 1 United States Patent; O

3,357,008 AUTOMATIC ALARM ANNUNCIATOR CIRCUITS Robert R. Walsh, Wilmington, Deli, assignor. to All American Engineering Company, WilmingtomDeL, a corporation of Delaware Filed Mar; 17, 1964, Ser. No. 352,516 Claims. (Cl. 340213.1)

This relates to. automatic alarm annunicator circuits and more particularlyto such circuits having silicon con: trolled rectifiers as the only active element or elements therein,

The circuits comprising the subject matter of this invention are used in applications relating to chemical and other industrial processes for the purpose of monitoring such variable process parameters as temperature, pressure, flow rate, and many. others. The transducer means associated with each parameter being monitored usually includes monitoring switches having either normally open or normally closed switch contacts which close or open, respectively, when the parameter. being monitored exceeds its normal prescribed limits.

These monitoring switches are each connected with alarm annunicator circuits which provide audible and visual indication at a remote point or points of an ab.- normal or oil-normal condition of a given parameter. The audible signal is of the horn or bell type while the visual signal is preferably aflashing light. The audible signal may be common to all points being monitored in a given process or the like but the visual signals are individually associated with each of the monitoring switches.

Each alarm annunciator circuit. is equipped with an acknowledge switch at the remote monitoring point which is adapted to be closed by the operating personnel for the purpose of acknowledging the operators awareness of. an abnormal condition. This switch deenergizes the audible alarm and changes the operating format of the visual alarm from flashing to steady for the purpose of indicating that the process is still malfunctioning but that the operating personnelare aware of this condition.

As soon as normal conditions are restoredythe visual alarm is restored to the state representing the said normal conditions.

The two generally preferred standards for alarm an nunciator circuitsinindustry are commonly referred to as Sequence A andSequence B.

In Sequence A operation the normal condition is signified by an extinguished visual alarm and a silenced audible alarm; the abnormal condition by a flashing visual signal and an energized audible alarm, and the acknowledge condition by a steady visual signal and a silenced audible alarm. Sequence B differs only in the provision of a dimly illuminated visual signal in the normal condition.

It is an object of this invention to provide new and novel alarm annunciator. circuits for both Sequence A and Sequence B operation.

Another object ofthis invention is to provide new and novel alarmannunciator circuits in which the only active circuit means comprise silicon controlled rectifiers.

Still another object of this invention is to provide new and novel alarm annunciator eircuitsin which when an abnormal condition response is initiated by only a momentary variation at the remote monitoring point, actuation of the acknowledge switch will result in a return of the system to the normal state, ratherthan to a conditionin which the visual. alarm is constantly energized.

These and other objects of this invention will become more fully apparent with reference to the following specification and drawings which relate to a preferred embodiment of the invention:

the visual alarm and sensing circuit otthe present inven-.

tion.

Referring in detail toFIGURE 1 one embodiment of the alarm annunciator circuit of the present invention is shown as comprising a first visual alarm and sensing cir-.

cuit. A and a second audible alarm circuit B.

The first circuit A is supplied with AC. power: from an AC. sourcelt) connected: betweenfirst and second power leads P1 andPZ via terminals T1 and T2, respectively, P2 being a common or the first circuit A.

The second circuit B is powered from the A.C.source 1%) via first andisecond extension leads P3 and P4 connected, respectively, to the first andsecond terminal T1 and T2 in the visual alarm circuit A and through termirials P9 and P10 in the audible alarm circuit D. The second extension lead P4, like the second power lead P2, is a common or potential reference lead forthe second circuit B.

The visual alarm means 12 comprises first and second signal lamps L1 and L2, respectively, connected in parallel. One. side of the said visual alarm means is connected to the common power lead P2 while the otherside is conpotential reference lead for nested through one .side of a visual alarm energizing circuit 14 to the first power lead P1.

The visual alarm energizing circuit 14 includes, as an active circuit element, a first silicon controlled rectifier SCRl, hereinafter referred to solely as SCRl, having anode, cathode. and gate terminals 16, 18 and 20;respectively. The anode terminal 16 is connected with the first power lead P1, the cathode terminal 18 is connected with the said other side of the said visual alarm means 12,.and the gate terminal 20 is connected with one side of a current limiting. first resistor R1, the other side of which is connected to a junctionpoint 22. The junction point 22is connected through a second resistor R2, with the common power lead P2. Optionally, the alarm trigger circuit 12 may include a first capacitor C1 connected between the cathode terminal 18 of the SCRI and the first power lead P1 for the purpose of by-passing transient pulses around the SCRl under operating conditions which pro duce these pulses.

A lead 24 extends from the junction point 22 to a third terminal T3 which isconnected withfirst switch contact 26 of a normally open transducer switch T additionally comprising a switch bar 28 and a second contact 30, the said contacts being adapted to be bridged by the said switch bar. The second contact 30; of the switch T is connected through a fourth terminal T4 to a third.

common lead P5 which is associated with a plurality of circuits to be hereinafter described.

A signal coupling circuit 32 for efiecting a triggering of the audible alarm when the .visual alarm istriggered is connected between the lead. 24 and the second common lead P2. The coupling circuit 32 comprises a second capacitor C2 connected at one side to the lead 24 and at the other, through a junction point 34 in. series with a third resistor R3 between the lead 24 and second common lead P2,. and a diode D1 connected at its anode to the said junction point 34 and at its cathode to a lead 36:

which leads to an output terminal T5.1

Theoutput terminal T5 in=thefirst circuit A is connected to a thirdterminal T11 in the second circuit B via a third extension lead P6.

A sixth terminal T6 in the first circuit A is connected 3,357,008 1 Patented Dec. 5, 1 967 3 comprising first and second ganged switch bars 38 and 40, respectively, is interconnected with the said sixth terminal T6.

The first switch bar 38 is adapted to bridge a first pair of contacts 42 which are in series in a lead 44 extending from the sixth terminal T6 to the common power lead P2.

The second switch bar 40 is adapted to bridge a second pair of contacts 46.

The acknowledge trigger circuit 48 includes a second silicon controlled rectifier SCR2, hereinafter refer-red to merely as SCR2, having anode, cathode and gate terminals 50, 52 and 54, respectively. Further included is a second diode D2 connected at its anode to the first common lead P1 and at its cathode to a junction point 56 which in turn is connected to one of the second pair of contacts 46 in the acknowledge switch SA via a lead 58. The other of the contacts 46 is connected with the gate terminal 54 of the SCR2 via a resistor R4.

The junction point 56 is joined with the anode terminal 50 of the SCR2 via a current limiting fifth resistor R5.

The cathode terminal 52 of the SCR2 is connected directly to the third common lead P while the anode terminal 50 is coupled to the said second common lead P2 through a third capacitor C3.

The anode terminal 50 of the SCR2 is further coupled to one side of a sixth resistor R6, the said resistor being coupled at its other end to a junction point 60.

The junction point 60 is coupled with the second common lead P2 via a fourth capacitor C4, and with the anode terminal 62 of a third silicon controlled rectifier SCR3, hereinafter referred to merely as SCR3. The SCR3 further includes a cathode terminal 64 connected with the third common lead P5 and a gate terminal 66. The gate terminal 66 of the SCR3 is connected to the anode terminal 62 thereof through a Zener diode D the latter having its anode at the said gate terminal 66 and its cathode at the said anode terminal 62 to complete a trigger circuit 68 for the visual alarm means 12.

For Sequence B operation of the first circuit A, a seventh resistor R7 shown in dotted lines is connected in shunt with the SCR3 from the first common line P1 to the cathode terminal 18 of the said SCR3.

When it is desired to use the first circuit A with detector switches which are normally closed, the terminals T3 and T4 thereof are short circuited by the dotted lead 70 and a normally closed transducer switch T comprising a switch bar 72 adapted to break the circuit between a pair of contacts 74. The contacts 74 are in series in a dotted lead 76 extending from the terminal T2 on the second common lead P2 to a terminal T7 which is directly connected with the anode terminal 50 of the SCR2 in the acknowledge trigger circuit 48.

The second circuit B, for audible alarm annunciation, is identical for both Sequence A and Sequence B operation and will now be described.

A first branch circuit comprising a third diode D3 and a fifth capacitor C5, connected in series through a common junction point 78, is connected between the common leads P3 and P4. The anode of the said third diode D3 is connected with the common line P3.

The junction point 78 is connected with another junc tion point 80 through an eighth resistor R8. The junction point 80, in turn, is connected directly to the terminal T12, is connected through a sixth capacitor C6 to the common lead P4, and is also directly connected to the anode terminal 82 of a fourth silicon controlled rectifier SCR4, hereinafter referred to merely as SCR4, which further includes a cathode terminal 84 and a gate terminal 86 and which comprises the active element of an audible alarm trigger circuit 88.

The gate terminal 86 of the SCR4 is directly connected with the terminal T11, is coupled with the common line P4 through a seventh capacitor C7 and is connected through a ninth resistor R9 with the gate terminal 90 of a fifth silicon controlled rectifier SCRS, hereinafter re ferred to merely as SCRS, which further includes an anode terminal 92 and a cathode terminal 94 and which comprises the active element of an audible alarm energizing circuit 96.

The cathode terminal 94 of the SCRS is directly connected with the common lead P4. The anode terminal is connected with a first common terminal 98 on the audible alarm means 160. A second common terminal 102 is provided on the opposite side of the audible alarm means 100 and is connected with the other common lead P3.

The electrical components of the audible alarm means, which is shown as a born or buzzer, comprise an eighth capacitor C8 a relay coil L and a fourth diode D4 all connected in parallel between the common terminals 98 and 102. The fourth diode D4 has its anode and cathode connected with the common terminals 98 and 102, respectively.

OPERATION Referring again to FIGURE 1 the operation of this embodiment of the invention in the Sequence A mode will now be described.

First, it is assumed that all conditions are initially normal in the system and that the normally open transducer switch T, is being used to effect the monitoring of a condition.

When the given condition becomes abnormal, the switch bar 28 makes the circuit through itself and the contacts 26 and 30, short-circuiting the terminal T3 and T4 and connecting the cathode terminal 64 of the SCR3 with the junction point 22 at the gate circuit of the SCRl via the third common lead PS, the said terminals T3 and T4 and the lead 24.

The current supplied to the fourth capacitor C4 via second diode D2, fifth resistor R5, and sixth resistor R6 charges fourth capacitor C4 to a potential equal to the positive peak potential of the AC. power supplied tocircuit A via terminal T1.

This potential is designed to exceed the breakdown potential of Zener diode D When transducer T closes it completes the cathode circuit of SCR3 from cathode terminal 64 via switch T junction 22, and resistor R2, to the second common lead P2. This permits Zener diode D to break down under the influence of the stored potential on fourth capacitor C4 and conduct a small current to the second common lead P2 via the gate terminal 66 of SCR3, the cathode terminal 64 of SCR3, switch T junction 22, and resistor R2. The small current through the gate of SCR3 triggers it into full conduction allowing the entire energy store of fourth capacitor C4 to flow as a large current pulse to second common lead P2 via anode terminal 62 of SCR3, cathode terminal 64 of SCR3, switch T junction 22, and resistor R2. The resistance oifered by R2 to this current pulse is suflicient to divert a portion of said current pulse through resistor R1 to the gate termi- I nal 20 of SCRl thus triggering SCRl into conduction capsing lamps L1 and L2. to flash for the duration of the pn se.

As long as the acknowledge switch SA is not closed by an operator, the capacitor C4 will alternately charge through D1, resistor R5 and resistor R6 and discharge through the SCR3, resistor R2 and resistor R1 to effect a flashing of the alarm lamps L1 and L2 at a rate determined by the time constant of the RC combination R5- R6-C4.

Since in the acknowledge trigger circuit 48 the combined resistance R5-R6-R2 is sutficient to prevent a sustaining current in the SCR3 when the capacitor C4 is discharged, the SCR3 is thus only fired in accordance with the said rate determined by the above-defined time constant. The anode supply to the SCRl is alternating current and thus provides a periodic interruption cutting off the SCRl.

The energy pulse from the SCR3 charges the second capacitor C2 in the output circuit 32 which discharges through the third resistor R3 and the coupling path comprising diode D1, lead 36, terminal T5, extension lead P6 This triggers the SCRS causing current to flow inthe audible. alarm energizing circuit 90 and sound the alarm The SCR4 is held on by way of the DC. voltage maintainedon the filter. capacitor C5 and C6 fed by the third diode D3.

The relay coil L of the audible alarm means 100 is held energized by the smoothing capacitor C8 in parallel there-. r

tected from; transient. surges from the relay coilL by the.

with and the SCRS. The audible alarm means 100. is pro-.

fourth diode D4.

Thus, at this stage in the operation, the first part of Sequence A operation has-been effected, namely, flashing. visual signal means 12 and continuous audible signal means 100.

Once an operator has noted the indicated abnormal condition sensed by the transducer T the acknowledge switch SA is:closed causing the switch bars 38. and 40 to bridge the contact pairs 42 and 46, respectively.

The filter. capacitor C6 is immediately shortcircuited throughthe switch bar and contacts 38 and 42, .via terminal T12, extension lead P7,and lead 44, the common leads P2 and P4 being at the same potential. This causes the.

voltage at the anode terminal 82 of the SCR4 to drop below that required to hold the SCR4 on and efiects its. cut:off.. When the 1SCR4 cuts off it removes the necessary sustainr ing bias from the gate terminal 90 of the SCRS which cuts off, silencing the audible alarm means 100.

At the same time, thegate terminal 54 of the SCR2 is connectedwith. the power source 10 through diode D2,.

junction 56,1ead 58, switch bar and contacts 40 and 46, respectively, and resistor R4 -resulting in the triggering of the SCR2.;

Because: of the capacitor C3, the SCR2 is continuously of the SCRZ and thus, the acknowledge switch SA need only be momentarily closed.

As soon as the condition being monitored returns to; normal, the transducer switch T opens and de-energizes the SCR2 and the SCRI, thusde-activating the acknowledge circuit 48 and the audible alarm energizing circuit 14, causing the alarm lamps L1 and L2 to be extinguished.

Thus, a complete Sequence A alarm annunciation cycle. 1

has been completed.

For the operation of the normally closed. transducer means Tc, the visual alarm trigger circuit 68 is short circui-ted by the line 76 across terminals T7 and T2 and thus, the audible alarm trigger circuit 88is also exeluded from operation. The third common lead P5, however, is connected with the lead 24 via the short 70 at.

terminals T3 and T4 and therefore, when an abnormal condition causes the switch bar 72 to break with the contacts 174, the operation of the system isidentical with that previously described.

For Sequence B operation, all of the operation for Sequence A is identical, the dilference being that a small current through the resistor R7 keeps the alarm lamps L1 and L2 dimly illuminated.

Because of its pulse type energization via the terminal T11 and its ready extinguishment via the terminal T12, the

audible alarmcircuit B may be in common connection 6 with a plurality of visual alarm circuits A. Thus, only one audible alarm means. is required formultitudinousvisual alarm means.

CIRCUIT RESPONSIVE TO MOMENTARY FAULTS Referring now to FIGURE 2, a second embodiment i A of the visual alarm and sensing circuit A, of FIGURE 1, will now be described, like elements to those of FIG- URE .1 bearing like numerals.

In this embodiment, the SCRI is alternativelyshunted I by a fifth half-wave diode D5, connected at its cathode 1 to the first power lead P1 and at its anode to the cathode terminal 18 of the SCRI for a purpose to be hereinafter described.

The trigger circuit 68*for the visual alarm means 112 is. connected directly with the alarm energizing circuit .14 i

by a lead 104 which. connects the cathode terrninaiz64 oi the aSCR3with the common node 22 in the gate circuit.

of the SCRI.

The visual ala-rrn trigger circuit 68 is selectively powered from the AC. source 10 via a sixth silicon controlled rectifier SCR6, hereinafter referred to merely as: SCR6, which also comprises an active element in an acknowledge trigger circuit 106. The SCR6 includes. an anode terminal108 connected via the diode D2 to the first .power lead P1, a cathode terminal 110=connected via the sixth resistor. R6 to the anode terminal .62 of the SCR3, and a gate terminal 112 comprising the common junction of a voltage. divider consisting of tenth and eleventh series resistors R10qand R11, respectively.

The resistor R10 is connected at its outer end with a junction point 114 common to both thethird circuit terminal T3 of the circuit A and the anode terminal 116 of a seventh silicon controlled rectifier SCR7,hereinafter referred to merely as SCR7, the said SCR7 further ineluding cathode and gate terminals 118 and 1-20, respectively. The resistor R11 is connected at its outer end with the cathode terminal 110 of the SCR6. A third capacitor C3 is connected between the anode 108 of the SCR6and the second or common power lead P2.

The cathode terminal 118 of the SCR'7 is connected Withthe outer terminal of the second capacitor C2 in the. signal coupling circuit 32.;

The gate terminal 120 of the SCR7 is connected via a twelfth resistor. R12 with the anode of a sixth diode D6, said anode being directly connected with one of the second pair of contacts 45 of the acknowledge switch ;SA. The cathode of the said sixth diode D6 is connected di- .rectly to the cathode terminal 110 of the SCR6.

The other of the second pairof contacts 46in the ac-: knowledge switch SA is connected directly to the anode terminal 108 of the SCRd via the series path comprising leads 122 and 124 and is connected to the fourthcircuit terminal T4 via the series path comprising leads 122 and: 126, thirteenth resistor R13 and lead 128.

The anode terminal 116 of the SCR7,.cornmon node ll4 and the third circuit terminal T3 are all connected. with the second or common power lead. P2 through a ninth capacitor C9,, ,thus completing the acknowledge trigger circuit 106.

The normally open transducer or detector switch T has its contacts 26 and 3% connected, respectively, with circuit terminals T3 and T4.

For using a normally closed detector switch Tc, the. pair of contacts 74 thereof are respectively connected to the circuit terminals T2 and T3; and the circuit terminals T3 and T4are additionally short circuitedvia a jumper as shown by dotted lines in FIGURE 2A As already illustrated in FIGURE 1, thecircuitterminals TL TZ, T5 and T6 of the sensing and visual alarm circuit A are to be interconnected with the terminals T9, T10; T11 and T12, respectively, of the audible alarm. circuit B.

7 OPERATION Referring further to FIGURE 2, the operation of this embodiment of the invention will now be described.

As previously described in conjunction with FIGURE 1, the SCRI controls the conduction of positive halfcycles of current from the A.C. power source 10' to the signal lamps L1 and L2 when gate signals of the proper magnitude are applied to the common junction 22 in the gate circuit of the SCRI.

The optional or fifth diode D is utilized during Sequence B operation whereby it continuously operates the lamps L1 and L2 on negative half-cycles from the AC. source 19 at the half-wave power level while, when the SCRI is switched on, the lamps L1 and L2 burn more brightly, being illuminated at the full-wave power level. This embodiment substantially eliminates the heat dissipation and heat rise caused by the resistor R7 in the embodiment of FIGURE 1.

The third capacitor C3 is charged via the second diode D2 to impose a DC. potential between the fourth circuit terminal T4 and the common power lead P2.

Assuming that the normally open detector switch T is connected as the remote or field sensing element, and further, that the contacts 26 and 30 thereof have been shorted by the contact bar 28, the positive potential stored in the third capacitor C3 is connected to the anode terminal 116 of the SCR7 via the series path comprising leads 124, 126, resistor R13, lead 128, terminals T4, transducer T terminal T3 and common junction 114. This potential is also applied via the common junction 114 and the voltage divider R10-R11 to the gate terminal 112 of the SCR6, whereby the SCR6 is triggered into the conductive state.

This causes positive half-cycles to be applied to the fourth capacitor C4 via resistor R6 causing it to charge to a potential exceeding the breakdown voltage of Zener diode D said potential being applied via anode terminal 62 of SCR3 to the visual alarm trigger circuit 68 which cooperates with the alarm energizing circuit 14, as already described in conjunction with FIGURE 1, to produce a flashing visual alarm via the lamps L1 and L2.

If the closing of the detecting transducer T has been of a momentary nature, the flashing signal will be initiated and then maintained because the. charge on capacitor C3 will maintain a DC. anode potential supply at the anode terminal 108 of SCR6 holding it in conduction. However, no DC. potential will be applied to the anode terminal 116 of the SCR7, and thus, when the second pair of contacts 46 of the acknowledge switch SA are closed by the circuit operator in response to the visual flashing and audible signals, no conduction of the SCR7 occurs. But the closing of said contacts 46 causes a shunting of the SCR6 through the sixth diode D6, resulting in the extinguishment of the SCR6 and the flashing signal lamps L1 and L2.

Had the closing of the detecting transducer T been prolonged, the positive potential at the anode terminal 116 of the SCR7 and the potential applied to the gate terminal 120 thereof via the leads 124 and 122, switch bar 40, and the second contacts 46 of the acknowledge switch SA would result in the conduction of the SCR7, effecting a shunt of the third capacitor C3, extinguishing the SCR6, and providing a steady gate signal present at the common junction 22 in the gate circuit adjacent the gate terminal of the SCRl via the cathode terminal 118 of the SCR7 and the lead 24. Thus, the SCRl is held in the conducting state to maintain a steady illumination in the signal lamps L1 and L2 commensurate with the previously defined acknowledged abnormal signal for both Sequence A and Sequence B operation.

In the case of using the sensing transducers TC, with normally closed contacts, the third circuit terminal T3 is held at the potential of the common lead P2 via the normally closed contacts 74 and switch bar '72 of the transducer TC. If these contacts 74, however, should open in response to an abnormal condition, this will permit the third circuit terminal T3 to rise to the same positive potential that exists across the third capacitor C3. At this point, because of the jumper lead across the third and fourth circuit terminals T3 and T4, the circuit A is in the same condition as it was initially when the normally open switch T 0 was closed. Thus, the subsequent operation for a prolonged opening of the normally closed switch TC is the same as previously described for the prolonged closing of the normally open switch T For a momentary abnormality, even though the third terminal T3 is returned to the potential of the common lead P2, the SCR6 has been triggered into conductivity and the anode terminal 116 of the SCR7 has been placed at the potential of the common lead P2. Thus, the closing of the acknowledge switch SA will not trigger the SCR7 and will result in a return of the signal lamps L1 and L2 in the circuit A to the state representative of a normal condition in the Sequence A or Sequence B operating modes, as the case may be.

As can be seen from the foregoing specification and drawings, this invention provides a new and novel alarm annunciator circuit means which is highly versatile and which has only silicon controlled rectifiers as its active elements.

It is to be understood that the embodiment of the invention shown and described herein is for the purpose of example only and is not intended to limit the scope of the appended claims.

What is claimed is:

1. In an alarm annunciator circuit including a power source, visual alarm means, and audible alarm means, means actuating said alarm means from an initial state to another in response to a predetermined condition comprising transducer means monitoring said condition, relaxation oscillator means selectively connected with said power source and actuated by said transducer means, first semiconductor switch means, periodically triggered by said relaxation oscillator means, connected with said source and said alarm means comprising intermittent energizing means for said visual alarm means, pulse generating means energized by said relaxation oscillator means, trigger means interconnected with and actuated by said pulse generating means, second semiconductor switch means for said audible alarm means interconnected with and actuated by said trigger means, and acknowledge means selectively deenergizing said audible alarm means and constraining said first semiconductor switch means to continuously energize said visual alarm means including means deactuating said trigger means and said relaxation oscillator means; wherein said relaxation oscillator means includes rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source, said cathode terminal being further coupled with said semiconductor.

switch means, capacitance means connected from said anode terminal to the said other side of said source, and a Zener diode connected between said anode terminal and said gate terminal.

2. The invention defined in claim 1, wherein said first semiconductor switch means comprises a silicon controlled rectifier having anode, cathode and gate terminals, said anode and cathode terminals being connected in series between said source and said visual alarm means and said gate terminal being coupled to said relaxation oscillator means.

3. The invention defined in claim 1, wherein said pulse generating means comprises a capacitor connected on one side to said relaxation oscillator means and a resistor in series therewith having a common junction therebetween, said resistor being connected with said power source, and a diode having anode and cathode terminals, connected at its anode to said common junction and at its cathode to relaxation oscillator means, connected with said source,

and said alarm means comprising intermittent energizing means for said visual alarm means, pulse generating means energized by said relaxation oscillator means, trigger means interconnected with and actuated by said pulse generating means, second semiconductor switch means for said audible alarm means interconnected with and actuated by said trigger means, and acknowledge means selectively deenergizing said audible alarm means, and constraining said first semiconductor switch means to continuously energize said visual alarm means including means deactuating said trigger means and said relaxation oscillator means; wherein said trigger means comprises rectifier means connected with one side of said source, first capacitance means in series therewith and connected with the other side of said source, a common junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction, second capacitance means connected between said anode terminal and the other side of said source, third capacitance means connected between said gate terminal and said other side of said source, and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal beingconnected with said pulse generating means and said cathode terminal being connected with said second semiconductor switch means.

5. The invention defined in claim 1, wherein said second semiconductor switch means comprises a silicon controlled rectifier having anode,,cathode and gate terminals, said anode and cathode terminals being connected in series between said source and said audible alarm means and said gate terminal being coupled to said trigger means,

6. In an alarm annunciator circuit including a power source, visual alarm means, and audible alarm means, means actuating said alarm means from an initial state to another in response to a predetermined condition comprising transducer means monitoring said condition, relaxation oscillator means selectively connected with said power source and actuated by said transducer means, first seimconductor switch means, periodically triggered by said relaxation oscillator means, connected with said source and said alarm means comprising intermittent energizing means for said visual alarm means, pulse generating means energized by said relaxation oscillator means, trigger means interconnected with and actuated by said pulse generating means, second semiconductor switch means for said audible alarm means interconnected with and actuated by said trigger means, and acknowledge means selectively deenergizing said audible alarm means and constraining said first semiconductor switch means to continuously energize said visual alarm means including means deactuating said trigger means and said relaxation oscillator means; wherein said acknowledge means comprises first switch means selectively shunting said source from said trigger means, second switch means, semiconductor switch means having anode, cathode and gate terminals, said anode and cathode terminals being connected in shunt with said relaxation oscillator means, said anode terminal being further connected with said second switch means and coupled with one side of said source, and said cathode terminal being connected with a load resistor common to said relaxation oscillator means and-coupled with said first semiconductor switch means, resistance means interconmeeting said second switch means and said gate terminal, and capacitance means interconnecting said anode terminaland the other side of said source.

7. In an alarm annunciator circuit including a power source, condition responsive transducer means and a visual alarm means, means for intermittently energizing said visual alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, including rectifier means connected with one side of said source,,re-

sistance means in series therewith, a silicon controlled,

rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source and having a common connection with said cathode terminal, capacitance means connected from said anode terminal to the other side of said source, and a Zener diode connected between said anode terminal and said gate terminal; and semiconductor switch means, including a gate terminal and resistance means interconnecting said gate terminal and said common connection, periodically triggered by said oscillator means, interconnected with said source and said alarm means.

8. In an alarm annunciator circuit including a power source, condition responsive transducer means and ,a

visual alarm means, means for intermittently energizing said visual alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, including rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals,,said anode terminal being coupled with said resistance means, a load resistor connected in series with, said cathode terminal and the other side, of said source and having a common connection with said cathode terminal, capacitance means connected from said anode terminal to the other side of said source, and a Zener diode connected between said anode terminal and said gate terminal; and semiconductor switch means, including, anode,: cathode and gate terminals, said anode and cathode terminals being connected in series with said source and said alarm means, and resistance means interconnecting said gate terminal and said common connection.

9. In an alarm annunciator circuit including a power source, condition responsive transducer means and a visual alarm means, means for intermittently energizing said visual alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, including rectifier means connected with one side of said source, resistance means in series therewith, a siliconcontrolled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminaland the other side of said source and having a common connection with said cathode terminal, capacitance means connected from said anode terminal to the other side of said source, and a Zener diode connected between said anode terminal and said gate terminal; and semiconductor switch means, including a gate terminal and resistance means interconnecting said gate terminal and said common connection, periodically triggered by said oscillator means, interconnected with said source and said alarm means, and means providing a minimum energization of said alarm means superimposed on said intermittent energization thereof.

10. In an alarm annunciator circuit including a power source, condition responsive transducer means and a visual alarm means, means for intermittently energizing said visual alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means including rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source and having a common connection with said cathode terminal, capacitance means connected from said anode terminal to the other side of said source, and a Zener diode connected between said anode terminal and said gate terminal; semiconductor switch means, including a gate terminal and resistance means interconnecting said gate terminal and said common connection, periodically triggered by said oscillator means, interconnected with said source and said alarm means; and acknowledge means including second semiconductor switch means in shunt with said silicon controlled rectifier and connecting said source with said load resistor, and selective control means energizing said second semiconductor switch means to thereby preclude intermittent energization of said alarm means by said oscillator means and continuously energize said first semiconductor switch means.

11. In an alarm annunciator circuit including a power source, condition responsive transducer means and a visual alarm means, means for intermittently energizing said visual alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means including rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source and having a common connection with said cathode terminal, capacitance means connected from said anode terminal to the other side of said source, and a Zener diode connected between said anode terminal and said gate terminal; first semiconductor switch means, including anode, cathode and gate terminals, said anode and cathode terminals being connected in series with said source and said alarm means, and resistance means interconnecting said gate terminal and said common connection; and acknowledge means including second semiconductor switch means having anode, cathode and gate terminals, said anode and cathode terminals being connected in shunt with said silicon controlled rectifier and said cathode terminal being further connected with said common connection, said anode terminal being further connected with one side of said source, capacitance means connected between said anode terminal and the other side of said source, switch means connected on one side with said anode means and resistance means interconnecting said gate terminal with the other side of said switch means.

12. The invention defined in claim 10, wherein said means further includes means providing a minimum energization of said alarm means superimposed on said intermittent energization thereof.

13. The invention defined in claim 11, wherein said means further includes means providing a minimum energization of said alarm means superimposed on said intermittent energization thereof.

14. In an alarm annunciator circuit including a power source, audible alarm means and condition responsive transducer means, means for energizing said audible alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, pulse generating means connected with said oscillator means and producing energy pulses in response to the energization of said oscillator means, trigger means actuated by said pulse generating means and semiconductor switch means energized by said trigger means and connected in series with said source and said 12 audible alarm means; said relaxation oscillator comprising rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means,

a load resistor connected in series with said cathode terminal and the other side of said source, said cathode terminal being further coupled with said semiconductor switch means, capacitance means connected from said anode terminal to the said other side of said source, and a Zener diode connected between said anode terminal and said gate terminal.

15. In an alarm annunciator circuit including a power source, audible alarm means and condition responsive transducer means, means for energizing said audible alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, and including a load resistor, pulse generating means connected in shunt with said load resistor producing energy pulses in response to the energization of said oscillator means and having an output; trigger means actuated by said pulse generating means including a resistance-capacitance input network connected across said source, a silicon controlled rectifier having anode, cathode and gate terminals, said gate terminal being connected with said output of said pulse generating means, said anode terminal being connected with said input network, and capacitance means coupling said gate terminal with one side of said source; and semiconductor switch means, including a resistance means and a gate terminal connected with said cathode terminal and coupled through said resistance means to the said gate terminal of said silicon controlled rectifier, connected in series with said source and said audible alarm means.

16. In an alarm annunciator circuit including a power source, audible alarm means and condition responsive transducer means, means for automatically energizing and selectively deenergizing said audible alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means, pulse generating means connected with said oscillator means and producing energy pulses in response to the energization of said oscillator means, trigger means actuated by said pulse generating means, semiconductor switch means energized by said trigger means and connected in series with said source and said audible alarm means, and acknowledge means selectively deenergizing said trigger means and thus deenergizing said semiconductor switch means said relaxation oscillator comprising rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source, said cathode terminal being further coupled with said semiconductor switch means, capacitance means connected from said anode terminal to the said other side of said source, and a Zener diode connected between said anode terminal and said gate terminal.

17. In an alarm annunciator circuit including a power source, audible alarm means and condition responsive transducer means, means for automatically energizing and selectively deenergizing said audible alarm means comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means and including a load resistor, pulse generating means connected in shunt with said load resistor producing energy pulses in response to the energization of said oscnlator means and having an output; trigger means actuated by said pulse generating means including a resistancecapacitance input network connected across said source, a silicon controlled rectifier having anode, cathode and gate terminals, said gate terminal being connected with said output of said pulse generating means, said anode 13 terminal being connected with said input network, and capacitance means coupling said gate terminal; with, one side of said source; semiconductor switch means, including a resistance means and a gate terminal connected with said cathode terminal and coupled through said re- 18. In an alarmannunciator circuit including a power source, condition responsive transducer means and a visual alarm means having a normally quiescent state of energizatiou, means for automatically energizing said talarm intermittently in response to both prolonged and momentary responses of said transducer means and subsequent to the respective ones of saidtresponses selectively energizing said alarm means continuously and returning said alarm means to its quiescent state, respectively, comprising relaxation oscillator means selectively connected with said power source and actuated by said transducer means,

semiconductor switch means periodically triggered by said 1 oscillator means interconnected with said source and said alarm means, and acknowledge means deenergizing said oscillator means and continuously energizing said semi conductor switch means in the event of said prolonged responses of said transducer means including first and sec ond semiconductor means, said first semiconductor means interconnected with and controlling the energization of said oscillator means, and said second semiconductor, means disabling said first semiconductor means, said oscillator means and said semiconductor switch means in the event of said momentary responses of said transducer, means and maintaining a state of energization in said semiconductor switch means in the event of said prolonged responses; said relaxationtoscillator comprising rectifier means connected withone side of said source, resistance means in seriesttherewith, a silicon controlled rectifier having anode, cathode t-and gate terminals; said anode ter-: minal being coupled with said resistance means, a load resistor, connected in series with said cathode terminal and the other side of said source, said cathode terminal being further coupled with ,aid semiconductor switch means, capacitance means connected from said anode terminal to the said other side, of said source, and a Zener diode connected between said anode terminal and said gate terminal.

19. In an alarm annunciator circuit including a power source, condition responsive transducertmeans and a visual alarm means having a normally quiescent state of energization, means for automatically energizing said alarm intermittently in response to both prolonged and momentary responses of said transducer means and subsequent to the respective ones of said responses selectively energizing said alarm means continuously and returning said alarm means to its quiescent state, respectively, comprising relaxation oscillator means selectivelyconnected with said power source and actuated by said transducer means, semiconductor switch means periodically triggered by said oscillator means interconnected with said source and said alarm means, and acknowledge means deenergizing said oscillator means and continuously energizing said semiconductor switch means in the event of said prolonged responses of said transducer means including first and second semiconductor means, said first semiconductor means interconnected with and controlling the energization of said oscillator means, and said second semiconductor means disabling said first semiconductor means, said oscillator means and said semiconductor switch means in the event of said momentary responses of said transducer means and maintaining a state of energization in said semiconductor switch means in thetevent of said prolonged responses; and means providing a minimum energization of said alarm means superimposed on all other conditions thereof comprising half-wave rectifier means in series with i said power source and said visual alarm means having the direction of conductivity therethrough opposite to the direction of conductivity through said semiconductor switch means.

20. In an alarm annunciator circuit including a power,

source, visual alarm means, and audible alarm means, means actuating said alarm means from an initialtstate to another in response to a predetermined condition comprising transducer means monitoring said condition, relaxation oscillator means: selectively connected with said power source and actuated by said transducer means, first semiconductor switch means periodically triggered by said oscillator means connected with said source and said alarm means comprising intermittent energizing means for said visual alarm means, pulse generating means energized by said oscillator means, trigger means interconnected with and actuated by said pulse generating means, second semiconductor switch means for said audible alarm means,

interconnected with and actuated by said trigger means, and acknowledge means selectively deenergizing said audible alarm means and constraining said semiconductor switch means to continuously energize said visual alarm means including means deactuating saidtrigger means,

silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source, said cathode terminal being furthercoupled with said semiconductor switch means, capacitance means c ni nected from said anode terminal to, the said other side i of said source, and a Zener diode connectedbetween said anode terminal and said gate terminal.

21. The invention defined in claim 20, wherein said semiconductor switch means comprises a silicon controlled rectifier having anode, cathode and gate terminals, said anode and cathode terminals being connected in series between said source and said visual alarm means and said gate terminal being coupled to said relaxation oscillator means.

22. The invention defined intclaim 20, wherein said pulse generating means, comprises a capacitor connected on one side to said relaxation oscillator means and a resistor in series therewith having a common junction therebetween, said resistor being connected withsaid power source, and a diode having anode and cathode terminals, connected at its anode to said common junction and at its cathode to said trigger means.

23. In an alarm annunciator circuit including a power source, visual alarm means, and audible alarm means, means actuating said alarm means from an initial state to another in response to a predetermined condition comprising transducer means monitoring said condition, relax ation oscillator means selectively connected with :said

power source and actuated by said; transducer means, first switch means to continuously, energize said visual alarm means including means deactuating said trigger means and said oscillator means in the event of a prolonged occurrence of said predetermined condition and further, in the event of a momentary occurrence of said predetermined condition, including means deactuating said semiconductor switch means to return said visual alarm means to its initial state and deactuating said trigger means and said oscillator means; wherein said trigger means comprises rectifier means connected with one side of said source, first capacitance means in series therewith and connected with the other side of said source, a common junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction, second capacitance means connected between said anode terminal and the other side of said source, third capacitance means connected between said gate terminal and said other side of said source, and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal being connected with said pulse generating means and said cathode terminal being connected with said second semiconductor switch means.

24. The invention defined in claim 20, wherein said second semiconductor switch means comprises a silicon controlled rectifier having anode, cathode and gate terminals, said anode and cathode terminals being connected in series between said source and said audible alarm means and said gate terminal being coupled to said trigger means.

25. In an alarm annunciator circuit including a power source, visual alarm means, and audible alarm means, means actuating said alarm means from an initial state to another in response to a predetermined condition comprising transducer means monitoring said condition, relaxation oscillator means selectively connected with said power source and actuated by said transducer means, first semiconductor switch means periodically triggered by said first oscillator means connected with said source and said alarm means comprising intermittent energizing means for said visual alarm means, pulse generating means energized by said first oscillator means, trigger means interconnected with and actuated by said pulse generating means, second semiconductor switch means for said audible alarm means interconnected with and actuated by said trigger means, and acknowledge means comprising first switch means selectively shunting said source from said trigger means, third semiconductor switch means in series with said source and said relaxation oscillator means, second switch means selectively shunting said source from said third semiconductor switch means, and fourth semiconductor switch means in circuit with said transducer means selectively shunting said source from said relaxation oscillator means and interconnected with said first semiconductor switch means wherein said relaxation oscillator means includes rectifier means connected with one side of said source, resistance means in series therewith, a silicon controlled rectifier having anode, cathode and gate terminals, said anode terminal being coupled with said resistance means, a load resistor connected in series with said cathode terminal and the other side of said source, said cathode terminal being further coupled with said first semiconductor switch means, capacitance means connected from said anode terminal to the said other side of said source, and a Zener diode connected between said anode terminal and said gate terminal.

26. The invention defined in claim 1, wherein said trigger means comprises rectifier means connected with one side of said source, first capacitance means in series therewith and connected with the other side of said source, a common junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction, second capacitance means connected between said anode terminal and the other side of said source, third capacitance means connected between said gate terminal and said other side of said source, and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal being connected with said pulse generating means and said cathode terminal being connected with said second semiconductor switch means.

27. The invention defined in claim 1, wherein said acknowledge means comprises first switch means selectively shunting said source from said trigger means, second switch means, semiconductor switch means having anode, cathode and gate terminals, said anode and cathode terminals being connected in shunt with said relaxation oscillator means, said anode terminal being further connected with said second switch means and coupled with one side of said source, and said cathode terminal being connected with a load resistor common to said relaxation oscillator means and coupled with said first semiconductor switch means, resistance means interconnecting said second switch means and said gate terminal, and capacitance means interconnecting said anode terminal and the other side of said source.

28. The invention defined in claim 1, wherein said trigger means comprises rectifier means connected with one side of said source, first capacitance means in series therewith and connected with the other side of said source, a common junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction, second capacitance means connected between said anode terminal and the other side of said source, third capacitance means connected between said gate terminal and said other side of said source, and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal being connected with said pulse generating means and said cathode terminal being connected with said second semiconductor switch means; and wherein said acknowledge means comprises first switch means selectively shunting said source from said trigger means, second switch means, semiconductor switch means having anode, cathode and gate terminals, said anode and cathode terminals being connected in shunt with said relaxation oscillator means, said anode terminal being further connected with said second switch means and coupled with one side of said source, and said cathode terminal being connected with a load resistor common to said relaxation oscillator means and coupled with said first semiconductor switch means, resistance means interconnecting said second switch means and said gate terminal, and capacitance means interconnecting said anode terminal and the other side of said source.

29. The invention defined in claim 20, wherein said trigger means comprises rectifier means connected with one side of said source, first capacitance means in series therewith and connected with the other side of said source, a common junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction, second capacitance means connected between said anode terminal and the other side of said source, third capacitance means connected between said gate terminal and said other side of said source, and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal being connected with said pulse generating means and said 17 cathode terminal being connected with said second semiconductor switch means.

30. The invention defined in claim 25, wherein said trigger means comprises rectifier means connected with one side of, said source, first capacitance means in series therewith and connected with the other side of said source, a common, junction between said rectifier and capacitance means, silicon controlled rectifier means having anode, cathode and gate terminals, resistance means connected between said anode terminal and said common junction,

second capacitance means connected between said anode terminaland the other sideof said source, third capacii tance means connected between said gate terminal and said other, side of said source,: and second resistance means coupling said gate terminal with said second semiconductor switch means, said anode terminal being connected with said acknowledge means, said gate terminal being connected with said pulse generatingmeans and said conductor switch means.

References Cited UNITED STATES PATENTS 3/1964 Foster 340-2132 6/1964 Silliman et a1. 340-213.1 4/ 1964 Snyder et a] 307- 885 1/1965 Ida 340-213.2 10/1965 Huttner 340 2132. 11/1965 Poster 340--213.2

FOREIGN PATENTS 7/1960 France.

THOMAS B. HABECKER, Acting Primary Examiner.

NEIL C. READ, Examinen R. ANGUS D. J. YUSKO, Assistant Examiners; 

1. IN AN ALARM ANNUNICATOR CIRCUIT INCLUDING A POWER SOURCE, VISUAL ALARM MEANS, AND AUDIBLE ALARM MEANS, MEANS ACTUATING SAID ALARM MEANS FROM AN INITIAL STATE TO ANOTHER IN RESPONSE TO A PREDETERMINED CONDITION COMPRISING TRANSDUCER MEANS MONITORING SAID CONDITION, RELAXATION OSCILLATOR MEANS SELECTIVELY CONNECTED WITH SAID POWER SOURCE AND ACTUATED BY SAID TRANSDUCER MEANS, FIRST SEMICONDUCTOR SWITCH MEANS, PERIODICALLY TRIGGERED BY SAID RELAXATION OSCILLATOR MEANS, CONNECTED WITH SAID SOURCE AND SAID ALARM MEANS COMPRISING INTERMITTENT ENERGIZING MEANS FOR SAID VISUAL ALARM MEANS, PULSE GENERATING MEANS ENERGIZED BY SAID RELAXATION OSCILLATOR MEANS, TRIGGER MEANS INTERCONNECTED WITH AND ACTUATED BY SAID PULSE GENERATING MEANS, SECOND SEMICONDUCTOR SWITCH MEANS FOR SAID AUDIBLE ALARM MEANS INTERCONNECTED WITH AND ACTUATED BY SAID TRIGGER MEANS, AND ACKNOWLEDGE MEANS SELECTIVELY DEENERGIZING SAID AUDIBLE ALARM MEANS AND CONSTRAINING SAID FIRST SEMICONDUCTOR SWITCH MEANS TO CONTINUOUSLY ENERGIZE SAID VISUAL ALARM MEANS INCLUDING MEANS DEACTUATING SAID TRIGGER MEANS AND SAID RELAXATION OSCILLATOR MEANS; WHEREIN SAID RELAXATION OSCILLATOR MEANS INCLUDES RECTIFIER MEANS CONNECTED WITH ONE SIDE OF SAID SOURCE, RESISTANCE MEANS IN SERIES THEREWITH, A SILICON CONTROLLED RECTIFIER HAVING ANODE, CATHODE AND GATE TERMINALS, SAID ANODE TERMINAL BEING COUPLED WITH SAID RESISTANCE MEANS, A LOAD RESISTOR CONNECTED IN SERIES WITH SAID CATHODE TERMINAL AND THE OTHER SIDE OF SAID SOURCE, SAID CATHODE TERMINAL BEING FURTHER COUPLED WITH SAID SEMICONDUCTOR SWITCH MEANS, CAPACITANCE MEANS CONNECTED FROM SAID ANODE TERMINAL TO THE SAID OTHER SIDE OF SAID SOURCE, AND A ZENER DIODE CONNECTED BETWEEN SAID ANODE TERMINAL AND SAID GATE TERMINAL. 